March 18, 2014

Sea Anemone Genetically Similar To Both Plants And Humans

Researchers lead by evolutionary and developmental biologist Ulrich Technau at the University of Vienna say that a sea anemone has a genomic landscape that is half animal, half plant.

Developmental biologists found that the genetic landscape of sea anemones features complex regulatory elements similar to that of fruit flies or other animal model systems. However, they also discovered that sea anemones are more similar to plants rather than vertebrates or insects.

The sequencing of genomes over the last few decades has revealed that anatomically simple organisms like sea anemones depict a surprisingly complex gene repertoire like higher model organisms. This implies that the difference in morphological complexity is not easily explained by the presence or absence of individual genes.

Some scientists believe that how gene codes are wired and linked to one another matters more to create complex body plans than the individual gene codes. The researchers expected that these gene networks are less complex in simple organisms than in human or “higher” animals.

Researchers identified promoters and enhancers on a genome-wide level in the sea anemone and compared the data to regulatory landscapes of more complex and higher model organisms.

"Since the sea anemone shows a complex landscape of gene regulatory elements similar to the fruit fly or other model animals, we believe that this principle of complex gene regulation was already present in the common ancestor of human, fly and sea anemone some 600 million years ago," Michaela Schwaiger of the University of Vienna, who was part of the research team, said in a statement.

The researchers were able to isolate 87 microRNAs from the sea anemone during the study. Plants microRNAs only bind to a handful of targets with high sequence specificity and induce with the aide of Argonaute proteins.

The team showed that the microRNAs of the sea anemone depict all the hallmarks of the plant microRNAs. They found that sea anemones have almost perfect complementarity to their target RNAs, which are subsequently cleaved and not inhibited like in other animals. The researchers also discovered a gene in the sea anemone that is essential for the microRNA biogenesis in plants and was never detected in any other animal model organism before.

The scientists concluded that while the sea anemone’s genome, gene repertoire and gene regulation on the DNA level is surprisingly similar to vertebrates, its post-transcriptional regulation is plant-like and probably dates back to the common ancestor of animals and plants. This finding provides insight on how important levels of gene regulation can evolve independently.